This proposal was previously reviewed by a special review committee and, as suggested by this committee, is now resubmitted as a small grant. Few, if any, patient groups require more mental health resources than the borderline personality disorder (BPD) patient. To date, there are no established specific pharmacologic interventions with demonstrated efficacy for BPD, but open-label and pilot data suggest that divalproex sodium (DS) may be effective in ameliorating core symptoms of BPD. Establishing the effectiveness of a pharmacologic intervention for this group would provide an important contribution to their treatment. This study represents a significant change in direction for a well-established research group. To date, our group has an established reputation as major contributors to research on the neurobiology and pharmacologic treatment of compulsive and impulsive disorders, such as obsessive compulsive disorder and body dysmorphic disorder. While our research has included important contributions to the understanding of the neurobiology of BPD, our treatment studies of BPD are limited. This small grant would enable us to gain additional experience in treatment research with this difficult population and enhance our ability to make future contributions in this important research area. We propose a small (R03) placebo controlled, double-blind study of the efficacy of DS in the treatment of global and specific symptoms of BDP to confirm our promising open treatment results. In addition, this small grant is necessary to better determine feasibility, power, response rates of drug and placebo-control groups and inter-rater reliability of outcome measures. This would provide the basis for a larger, well controlled research project. Specifically, it would enable us to gather further preliminary data in anticipation of an RO1 application for a full-scale study in this pharmacologic area.